Self-designed tattoos are fashionable technology

These tattoos are not just wearable art. They also let people interact with their electronics.

Jimmy Day/MIT

This is one in a series presenting news on technology and innovation, made possible with generous support from the Lemelson Foundation.

Ever wish your temporary tattoo could do more than just make an artistic statement? Researchers have created a new type that can sense touch, such as a finger-tap or swipe. The purpose? It allows you to wirelessly control electronic devices.

Wearable electronics aren’t new. Health monitors that attach to the skin can be used to track heart rate, blood-sugar levels and other body features. Those monitors are thin. They’re also stretchy, which keeps them from falling off when our skin flexes. But they aren’t pretty. And they tend to be quite pricey due to the materials used to make them.

Three computer scientists at the Massachusetts Institute of Technology in Cambridge wanted to change that. One of them, Cindy Kao, is also an artist. She pictured tattoos that not only were functional, but also fashionable and affordable.

To create them, she and her MIT colleagues Andres Calvo and Chris Schmandt teamed up with researchers at Microsoft Research in Redmond, Wash. Their first step was to identify a skin-safe material that conducts electricity. Their solution was imitation gold leaf. This thin (about one micrometer thick) sheet of metal isn’t actually gold. It’s mainly copper. It conducts electricity well and most art-supply stores sell it. That was important to Kao, who wanted people to be able to design and craft their own tattoos.

Next, the MIT trio developed the process to create those tattoos. They cut a design from a thin sheet of vinyl. This became their stencil. They then glued several layers of gold leaf onto tattoo paper using the stencil as a guide. (Tattoo paper has a special adhesive that holds the gold leaf to the skin.) The final step was to add a top layer of tattoo paper. The sparkly product was then ready to be applied to the skin using water, just like an ordinary temporary tattoo.

For these fashion accessories to “talk” to electronics, the researchers added either a communications device. A Bluetooth device uses radio waves to share information between two devices located up to 100 meters (about 330 feet) from each other. Bluetooth allows someone’s smartphone to communicate with their car radio or wireless headphones.

Bluetooth picks up a touch on this trackpad.

Jimmy Day/MIT

Another option: adding a near field communication tag. These tags create a small magnetic field to share information between two devices. But that sharing works only across very short distances — no more than 4 centimeters (1.6 inches). This technology lets some smartphones communicate simply by bringing them close. It also allows people to pay for things at the store by tapping their phone against a payment terminal.

Kao added this remote capability to the tattoos by cutting a tiny hole in the tattoo paper. (This happened before the tattoo was applied to the skin.) For tattoos that use Bluetooth, she slid the ends of two small wires inside. One end of each wire touched the gold leaf. The other connected to a Bluetooth device that wearers could hide under their clothes. Near field communication tags were added in the same way. But these tags are wireless. Kao inserted both ends of the tags into the gold leaf design, creating an electronic circuit.

How this new tech performs

The MIT team recruited people to try out the new tattoos, which they’re calling DuoSkin. To test durability, 10 people each wore a tattoo on their arm throughout a normal 8-hour work or school day. They also wore a strip of copper tape and a piece of electricity-conducting thread. By day’s end, the threads and tape had fallen off many recruits. Only the tattoos were still on the arms of all 10 people.

The team tested Bluetooth technology by having wearers control a music player using their tattoos. The tattoos had built-in buttons, sliders or touchpads. Users could change songs and adjust volume with a tap or swipe. The researchers also tested the ability of tattoos and smartphones to “talk” using near field communication. Phones brought within 1.4 centimeters (0.6 inch) of the tattoo picked up the tag’s frequency. That’s well within the expected range, Kao notes.

The tattoos are “an important step towards wider acceptance of skin electronic technology,” says Yael Hanein. An electrical engineer, she works at Tel Aviv University in Israel. The new designs show wearable tech can be both attractive and inexpensive. And that takes the technology “beyond medical application towards wider consumer use,” she says.

One day, such customizable fashion accessories could control the devices used for everything from medicine to communications and entertainment.

Cindy Kao talks about how to make temporary tattoos, called DuoSkin, with which people can control electronic devices. From MIT Media Lab on Vimeo.

Power Words

circuit A network of that transmits electrical signals. In the body, nerve cells create circuits that relay electrical signals to the brain. In electronics, wires typically route those signals to activate some mechanical, computational or other function.

colleague Someone who works with another; a co-worker or team member.

copper A metallic chemical element in the same family as silver and gold. Because it is a good conductor of electricity, it is widely used in electronic devices.

electricity A flow of charge, usually from the movement of negatively charged particles, called electrons.

electronics Devices that are powered by electricity but whose properties are controlled by the semiconductors or other circuitry that channel or gate the movement of electric charges.

engineer A person who uses science to solve problems. As a verb, to engineer means to design a device, material or process that will solve some problem or unmet need.

frequency The number of times a specified periodic phenomenon occurs within a specified time interval. (In physics) The number of wavelengths that occurs over a particular interval of time.

heart rate Heart beat; the number of times per minute that the heart — a pump — contracts, moving blood throughout the body.

information (as opposed to data) Facts provided or trends learned about something or someone, often as a result of studying data.

magnetic field An area of influence created by certain materials, called magnets, or by the movement of electric charges.

micrometer (sometimes called a micron) One thousandth of a millimeter, or one millionth of a meter. It’s also equivalent to a few one-hundred-thousandths of an inch.

monitor To test, sample or watch something, especially on a regular or ongoing basis.

near field communication A technology that allows different devices to communicate wirelessly with each other, sharing data across short distances. The devices do this through use of a magnetic field. Communi9cating devices do not need to touch each other or go through multiple steps to initially set up a connection.

radio waves Waves in a part of the electromagnetic spectrum; they are a type that people now use for long-distance communication. Longer than the waves of visible light, radio waves are used to transmit radio and television signals; it is also used in radar.

range The full extent or distribution of something. For instance, a plant or animal’s range is the area over which it naturally exists. (in math or for measurements) The extent to which variation in values is possible. Also, the distance within which something can be reached or perceived.

recruit (in research) New member of a group or human trial, or to enroll a new member into a research trial. Some may receive money or other compensation for their participation, particularly if they enter the trial healthy.

smartphone A cell (or mobile) phone that can perform a host of functions, including search for information on the Internet.

stencil A picture or pattern that is created by temporarily holding a shape or cutout against a surface and then applying some paint or pigment along the internal or external edges of that shape or cutout. If paint is applied along the outside edges, the surface will depict the unpainted shape of the object, with sharply defined, clean internal edges. If a cutout is used, the painted shape will depict the pattern of the cutout, with sharply defined, clean external edges.

technology The application of scientific knowledge for practical purposes, especially in industry — or the devices, processes and systems that result from those efforts.

terminal The end point or last station in some system, network or process. The end of the line.

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